In controlling various kinds of equipment in homes and buildings, the equipment is often connected to a network through which information is transmitted. Connecting the equipment together in a network system has the advantage that various parts of the system can "communicate" with each other, whereby the system works with maximum efficiency and potential inconsistencies, such as two parts of the system counteracting each other in operation, can be avoided.
A controller area network may, for example, be used for such purposes. Messages of variable length are transmitted in the network for controlling the system to operate according to provided algorithms. The message frame format includes an identifier at the beginning of each message which provides an identity for each message. The identity may, for example, relate to the kind of data transmitted in a data field of the message.
In a system including several similar producers of equivalent information, and including at least one ultimate consumer of the information produced by the producers, the system must facilitate that the consumer knows to which producers to listen. It is also important that the network is not overloaded with messages from those producers to which the consumer is not listening.
One way of arranging a system in accordance with the above would be to configure every producer particularly for its designated role in the system, and for the ultimate consumer to make use of addressing of the producers in the network. However, this method is undesirable in that it requires more initial programming and system configuration than is desirable for the typical home and building control system. Besides the additional work requirement, which may be inconvenient in a home or building environment, the costs of installation will likely increase with such a solution. Furthermore, the amount of information transmitted in the network may typically increase with this method, perhaps making the system harder to manage. An additional disadvantage is that producers cannot be added, and/or removed from the system without particular reconfiguration and/or readdressing of the producers.